Charging or discharging control circuit and battery device

Abstract

A charging or discharging control circuit includes a constant current source that flows a detection current, multiple voltage detection circuits connected in parallel to each of multiple secondary batteries, and a control circuit that receives outputs of the voltage detection circuits. The voltage detection circuit includes a voltage dividing circuit that outputs a divided voltage based on an input voltage between a positive input port and a negative input port, a reference voltage source that outputs a reference voltage, a first comparator circuit that receives and compares the divided voltage and the reference voltage, a second comparator circuit that receives and compares potentials of the positive input port and the negative input port, and switches that block an input voltage to the first comparator circuit. The control circuit, in response to the intermediate terminal being detached, blocks the input voltage to the first comparator circuit.

What is claimed is: 
     
         1 . A charging or discharging control circuit, comprising:
 a positive power source connection terminal, an intermediate terminal, and a negative power source connection terminal, which are respectively connected to a positive terminal, a battery interconnecting terminal, and a negative terminal of a plurality of secondary batteries connected in series;   a constant current source, flowing a detection current between the positive power source connection terminal and the intermediate terminal, between adjacent intermediate terminals, and between the intermediate terminal and the negative power source connection terminal;   a plurality of voltage detection circuits, connected in parallel to each of the plurality of secondary batteries; and   a control circuit, receiving outputs of the plurality of voltage detection circuits,   the voltage detection circuit comprising:   a voltage dividing circuit, outputting a divided voltage based on an input voltage between a positive input port and a negative input port;   a reference voltage source, outputting a reference voltage;   a first comparator circuit, receiving and comparing the divided voltage and the reference voltage;   a second comparator circuit, receiving and comparing potentials of the positive input port and the negative input port; and   a switch, blocking an input voltage to the first comparator circuit, and   wherein the control circuit, in response to the intermediate terminal being detached,   based on a detection signal output by the second comparator circuit,   blocks the input voltage to the first comparator circuit.   
     
     
         2 . The charging or discharging control circuit according to  claim 1 , wherein the constant current source has a period during which the detection current does not flow. 
     
     
         3 . A battery device, comprising:
 a plurality of secondary batteries connected in series; and   a charging or discharging control circuit according to  claim 1  that controls charging or discharging of the plurality of secondary batteries.   
     
     
         4 . A battery device, comprising:
 a plurality of secondary batteries connected in series; and   a charging or discharging control circuit according to claim  2  that controls charging or discharging of the plurality of secondary batteries.